CBSE 2025 · Region 1 · Set 1 · Q28 · 3 marks
With the help of an activity, explain the conditions under which iron articles get rusted.(b)Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water.(ii)Write a test to identify the gas evolved (if any) during the reaction of these metals with water.
With the help of an activity, explain the conditions under which iron articles get rusted.
(b)
Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water.
(ii)
Write a test to identify the gas evolved (if any) during the reaction of these metals with water.
Marking-scheme solution
Take three test tubes and place clean iron nails in each of them.
Label these test tubes A, B and C.
Pour some water in test tube A and cork it.
Pour boiled distilled water in test tube B, add about $\displaystyle 1$ mL of oil and cork it. The oil will float on water and prevent the air from dissolving in the water.
Put some anhydrous calcium chloride in test tube C and cork it. Anhydrous calcium chloride will absorb the moisture, if any, from the air.
Iron nails rust in test tube A, but they do not rust in test tubes B and C.
Rusting of iron takes place when exposed to both air and water.
Iron nails rust in test tube A, but they do not rust in test tubes B and C. Rusting of iron takes place when exposed to both air and water.
(b)
Sodium, Potassium, Lithium
Observations:
A violent reaction occurs.
Large amount of heat is evolved.
Evolved gas may catch fire.
(ii)
The gas (bubbles) burns with a pop sound
Metals and Non-metalsCorrosion and its PreventionUnderstandshort_answermedium
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CBSE Class 10 Science past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.